If you're going to buy real soon, get it at NCIX.
They have a $25 MIR until September 15th, but you get until October 15th to get it mailed. My experience with Seasonic MIR's have been extremely good since their rebate centre is in Ontario. But be warned they give you cheques in USD, make sure you don't get hit by a conversion fee at your bank.

PM it here. That makes it $155+taxes/shipping-$25MIR, pretty good for one of the best PSUs on the market.

I use a silverstone strider plus 850W and I can't cmoplain of it. The seasonic X is also a dead nice monster. I have one on hand actually that I put in a friend system, playing with it a bite while waiting for the other part:P